There are numerous embodiments for containers for distributing doses of treatment fluid, comprising a dosing device mounted in the neck of the container, the container being intended to function with the neck pointed towards the bottom, alternatively immersed in and taken out of a mass of water, in particular a toilet tank.
In the first embodiment, which has numerous variations, the dosing device comprises a float suspended under the neck of the container, fixed to one or two mobile valves operating together with one or two fixed seats accommodated in the neck of the container (patents: French 2 572 749, European 182 671, U.S. Pat. Nos. 4,346,483, 4,285,074, 3,778,850, 3,774,808, 3,698,021, 2,722,394, 2,967,310, 3.908,209, 3,841,524, 4,189,793, 4,131,958, 2,726,406, 4,036,407, 4,066,187, 3,965,497). This first embodiment is based on the principle that the variation of the water level in the water tank causes ascending or descending vertical slide of the float which itself causes the opening and closing of the valve or valves, which are of a mechanical or air type. According to certain variations, the valves, the seats and the neck of the container are put together to create the dosage chambers, with the aim of issuing defined doses of treatment fluid. Containers with dosing devices according to this first embodiment have the disadvantages that their functioning is linked to the movement of the float with all resulting imprecisions; that the halting of the flow is very random; that the mechanical-type closures are rather weak; and finally numerous pieces are required.
In a second embodiment, a discharge hole is accommodated in a transverse wall distanced from the free edge of the neck accomodating an air chamber. The container is only partially filled with the maintenance fluid. This second embodiment is based on the principle that the rise in the water level in the water tank above the free edge of the neck traps a mass of air in the air chamber. Then, when the level continues to rise, this mass of air is compressed and, when there is sufficient excess pressure, partially ejected into the container above the treatment fluid or it causes a certain excess pressure in relation to the external atmosphere. When the level of water in the water flush goes down to below the free edge of the neck, the excess pressure which exists in the air chamber disappears, as a result of its contact with the external atmosphere. The excess pressure existing in the container causes the expulsion of the treatment fluid until there is an equilibrium of pressure again on both sides of the discharge hole. This second embodiment is described in U.S. Pat. Nos. 3,806,965, 3,787,904, 3,864,763, 2,688,754, 3,073,488 and English patents 710 796, 2 094 846. This second embodiment has two advantages over the previously described first embodiment. On one hand, a "hydraulic" function resulting from the single variation of pressure in the time following the filling and emptying of the water tank and the resulting difference in pressure between one side of the discharge hole and the other, this functioning being theoretically continuous in contrast to the "mechanical" functioning operating the drive of a float commanding one or more valves which eventually jam causing functioning to be forcably discontinued. Meanwhile, the forms of execution of this second embodiment have the disadvantage that, from the functioning principle, the quantity of maintenance fluid issued is not invariable in the period, as soon as the container is emptied itself. In effect, as soon as the container is emptied, on one hand, the hydrostatic pressure exerted by the maintenance fluid on the discharge hole reduces and, on the other hand, the volume of air in the container which must have excess pressure to evacuate the maintenance fluid, increases.